This research program is concerned with investigating functional processes in the normal retina, with particular attention to the visual cells and pigment epithelium. A major objective is elucidation of metabolic phenomena in these specific cell types, particularly those processes involved in renewal mechanisms in the mature eye. By means of conventional and electron microscope autoradiography, the work is designed to trace the life history of biologically significant molecules from intracellular sites of synthesis to sites of degradation. Specific projects are proposed which deal with intermediate (or transmuted) visual cells, disc-shedding by cones, regeneration of cone outer segments after hibernation or cold-stress, and the formation and renewal of specific compounds in visual cells. A significant goal is the establishment, through animal studies, of biological generalizations which ultimately can contribute to the understanding of human vision.